The Chemistry of Wine

At its simplest, the process of making wine comes down to an issue of crushing some wine grapes and placing them in a tank with some yeast, then waiting while the grape sugars transform themselves into alcohol. That’s precisely what the Etruscans did when they made the world’s first wine at the end of the second century B.C. Professional winemakers, however, cannot afford such a hit-or-miss proposition.

It was Louis Pasteur who made a science of it all, discovering in 1857 that fermentation wasn’t such a wholly spontaneous phenomenon as had been previously imagined. He found it to be the work of enzymes, which would readily adapt themselves to certain processes, and this promptly gave birth to a new science called “Oenology.”

Today, winemakers and oenologists can control the chemical process of making wine to a degree that has enormous influence on the final taste and quality of their product. Length of contact with the grape skins, adjustment of fermentation temperatures, introduction of hybrid yeasts, inhibition of other wild yeasts, pumping juice from the bottom to the top of a tank, using wood barrels as the fermentation vessel, and a myriad of other techniques can all have a marked difference on how a wine tastes. Great wine is, indeed, “made in the vineyard,” but what can be achieved in the cellar also makes an important contribution.